One of the methods by which we prepare P25 photocatalyst is by depositing AgBr on surface of TiO2 (P25). Will depositing of Ag/AgBr on TiO2 surface and then annealing it at 500C cause some Ag+ ion to diffuse into TiO2 lattice and displace Ti forming substitutional vacancies?
I don't think so. Ag ions have charge +1, Ti can be +3 in deffects but most of it is +4. Ag(I) is also much bigger than Ti(IV), this would make the lattice really unstable.
Dear Rohit,
Rather than the incorporation of Ag+ into the TiO2 structure, which is not in line with any of Vegards rules, a ternary phase namely Ag2TiO3 at the interface will be formed. Please have a look at his paper:
Article Synthesis and Crystal Structure of Disilvertitanate-(IV), Ag 2TiO 3
All the best,
Thomas
Esfandfard, Seyed Mahmoud, Mohammad Reza Elahifard, Reza Behjatmanesh-Ardakani, and Hadi Kargar. "DFT study on oxygen-vacancy stability in rutile/anatase TiO2: effect of cationic substitutions." Physical Chemistry Research 6, no. 3 (2018): 547-563.
Azeez Abdullah Barzinjy Thomas Jüstel Luiz Fernando de Sousa Lima Thank you for your input. I most certainly agree with the idea that "Irrespective of the method of synthesis" (sol-gel method or photodeposition), the idea of Ag forming substitutional vacancies in TiO2 crystal is not rooted in theoretical observation. However, I do believe that Ti-O-Ag bonds are formed which somehow reduce the charge density and affect the lattice constants, thereby affecting the crystal strain however I am still working on proving this theory. The following paper has also reported the presence of Ti-O-Ag bonds. Perhaps oxygen vaccancies and its quantification is a good place to start.
Article Preparation and Photocatalytic Property of Ag Modified Titan...
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